tetanus

My wife had surgery 15 days ago for tongue cancer where the base of her tongue and floor of the mouth (right side) was removed, and also surgery on the right side of her neck to remove nodes. A 7-8 hour operation. Her muscles on that side are tight and causing spasams at times. She is concerned about tetanus. She does not know when she had her last tetanus shot. What are the chances of getting tetanus after neck and mouth surgery? Or what should I look for?